
    <!DOCTYPE html>
    <html lang="zh-CN">
    <head>
      <meta charset="UTF-8">
      <meta name="viewport" content="width=device-width, initial-scale=1.0">
      <title>Kafka的主从同步 - 交互式测验</title>
      <style>
        @import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;500;700&display=swap');
        
        body {
          font-family: 'Noto Sans SC', sans-serif;
          background-color: #f4f7f9;
          color: #333;
          display: flex;
          justify-content: center;
          align-items: center;
          min-height: 100vh;
          margin: 0;
          padding: 20px;
          box-sizing: border-box;
        }
        
        .main-wrapper {
            position: relative;
            width: 100%;
            max-width: 900px; /* Wider to accommodate buttons */
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .quiz-container {
          background-color: #ffffff;
          border-radius: 16px;
          box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
          width: 100%;
          max-width: 700px;
          overflow: hidden;
          z-index: 10;
        }

        .quiz-header {
          background-color: #4a90e2;
          color: white;
          padding: 20px 30px;
          text-align: center;
        }

        .quiz-header h1 {
          margin: 0;
          font-size: 24px;
          font-weight: 700;
        }
        
        .quiz-header p {
            margin: 5px 0 0;
            font-size: 14px;
            opacity: 0.9;
        }

        .quiz-body {
          padding: 30px;
        }

        .progress-bar {
            display: none; /* 隐藏进度条 */
            width: 100%;
            background-color: #e0e0e0;
            border-radius: 5px;
            height: 10px;
            margin-bottom: 20px;
        }

        #progress-indicator {
            height: 100%;
            width: 0%;
            background-color: #4caf50;
            border-radius: 5px;
            transition: width 0.3s ease;
        }

        #question-container {
          margin-bottom: 20px;
        }

        #question-text {
          font-size: 18px;
          font-weight: 500;
          line-height: 1.6;
          margin-bottom: 25px;
        }

        .options-list {
          list-style: none;
          padding: 0;
          margin: 0;
        }

        .option-item {
          background-color: #f8f9fa;
          border: 1px solid #dee2e6;
          border-radius: 8px;
          padding: 15px;
          margin-bottom: 12px;
          cursor: pointer;
          transition: background-color 0.2s ease, border-color 0.2s ease;
        }

        .option-item:hover {
          background-color: #e9ecef;
        }
        
        .option-item.selected {
            background-color: #d1e7fd;
            border-color: #4a90e2;
        }

        .quiz-footer {
          padding: 20px 30px;
          display: flex;
          justify-content: space-between; /* 将按钮分布在两侧 */
          align-items: center;
          min-height: 65px; /* Reserve space */
        }

        .nav-btn {
          background-color: #4a90e2;
          color: white;
          border: none;
          border-radius: 8px;
          padding: 10px 20px;
          font-size: 16px;
          font-weight: 500;
          cursor: pointer;
          transition: background-color 0.2s ease, transform 0.2s ease;
          box-shadow: 0 4px 12px rgba(0,0,0,0.15);
        }
        
        #next-btn {
            background-color: #28a745;
        }

        .nav-btn:hover {
          background-color: #357abd;
          transform: scale(1.05);
        }
        
        .nav-btn:disabled {
            background-color: #a0c3e8;
            cursor: not-allowed;
            opacity: 0.7;
        }

        #result-container {
            border-top: 1px solid #eee;
        }
        
        .result-box {
            border-radius: 8px;
            padding: 20px;
            margin-top: 20px;
        }
        
        .result-box.correct {
            background-color: #d4edda;
            border: 1px solid #c3e6cb;
            color: #155724;
        }

        .result-box.incorrect {
            background-color: #f8d7da;
            border: 1px solid #f5c6cb;
            color: #721c24;
        }
        
        .result-box h3 {
            margin-top: 0;
        }

        .explanation-text {
            margin-top: 15px;
            line-height: 1.7;
        }
        
        .source-text {
            font-style: italic;
            font-size: 14px;
            margin-top: 15px;
            color: #555;
        }

        
        .final-score-container {
            padding: 40px;
            text-align: center;
        }
        .final-score-container h2 {
            margin-top: 0;
            margin-bottom: 30px;
        }
        .score-summary {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin-bottom: 40px;
            flex-wrap: wrap;
        }
        .score-card {
            background-color: #f8f9fa;
            border-radius: 12px;
            padding: 20px;
            width: 180px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.05);
            border: 1px solid #e9ecef;
        }
        .score-card h3 {
            margin: 0 0 10px;
            font-size: 16px;
            font-weight: 500;
            color: #555;
        }
        .score-card p {
            margin: 0;
            font-size: 28px;
            font-weight: 700;
            color: #333;
        }
        .score-details table {
            width: 100%;
            font-size: 16px;
        }
        .score-details td {
            padding: 4px 0;
        }
        .score-details td:last-child {
            text-align: right;
            font-weight: 700;
        }
        .report-actions button {
            background-color: #fff;
            border: 1px solid #ccc;
            border-radius: 8px;
            padding: 12px 25px;
            font-size: 16px;
            cursor: pointer;
            margin: 0 10px;
            transition: background-color 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
        }
        .report-actions button:hover {
            background-color: #f1f1f1;
            border-color: #bbb;
            transform: translateY(-2px);
        }
        .report-actions button.primary {
            background-color: #28a745;
            color: white;
            border-color: #28a745;
        }
        .report-actions button.primary:hover {
            background-color: #218838;
        }
        
        .hint-container {
            background-color: #e0f7fa;
            border: 1px solid #b2ebf2;
            border-radius: 8px;
            padding: 15px;
            margin-top: 20px;
            color: #006064;
            font-size: 15px;
            line-height: 1.6;
            display: none; /* 默认隐藏 */
        }
      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Kafka的主从同步 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "在Kafka中，ISR (In-Sync Replicas) 同步副本集的核心职责是什么？",
    "options": [
      "存储整个集群的元数据备份，以防止ZooKeeper发生故障。",
      "在分区的多个副本之间平均分配消费者的读取请求，以提高性能。",
      "维护一个与Leader完全同步的副本集合，并在Leader故障时从中选举新Leader以保证数据不丢失。",
      "专门用于管理不同消费者组的偏移量（Offset）信息。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "ISR是Kafka保证高可用性和数据一致性的核心机制。它由Leader副本和所有与Leader数据保持完全同步的Follower副本组成。当Leader发生故障时，Kafka会从这个集合中选择一个副本作为新的Leader，因为ISR中的副本拥有最新的数据，这样可以有效防止消息丢失。",
    "source": "文档中「ISR（In-Sync Replicas）同步副本集」和「故障恢复」部分",
    "hint": "文档中提到：'只有那些与Leader完全同步的副本才会被包含在ISR中...在Leader故障时，Kafka会从ISR中选举出新的Leader，确保数据不会丢失。'"
  },
  {
    "question": "在一个具有多个副本的Kafka分区中，Leader副本扮演着什么独特的角色？",
    "options": [
      "它仅负责协调Follower副本之间的数据同步，不直接处理客户端请求。",
      "它是唯一负责处理所有生产者写入和消费者读取请求的副本。",
      "它与所有Follower副本共同分担来自消费者的读取请求。",
      "它主要负责在自身发生故障时，从Follower中选举出新的Leader。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "根据文档描述，Leader副本是分区的核心，所有的数据读写操作都必须经过它。生产者将消息发送给Leader，消费者从Leader读取消息。Follower副本的主要职责是从Leader同步数据，作为备份，正常情况下不处理客户端的读写请求。",
    "source": "文档中「主副本（Leader）」部分",
    "hint": "请回想文档中对Leader角色的定义：'Leader是分区中唯一负责处理所有生产者写入和消费者读取请求的副本。'"
  },
  {
    "question": "如果一个生产者需要为金融交易系统发送消息，绝对不能容忍任何数据丢失，应该如何配置`acks`参数？",
    "options": [
      "acks=0，因为它提供最低的延迟，对交易系统至关重要。",
      "acks=1，因为它在性能和可靠性之间取得了最佳平衡。",
      "acks=-1 (或 all)，因为它能确保消息被写入Leader和ISR中的所有副本后才返回成功确认。",
      "acks=2，因为它代表消息至少写入了Leader和一个Follower。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "配置为 `acks=-1` (或 `all`) 提供了最高级别的数据一致性保证。在这种模式下，生产者会等待分区的Leader以及ISR（同步副本集）中的所有Follower都成功写入消息后，才会收到确认。这可以最大限度地防止因Broker故障导致的数据丢失，尽管会增加写入延迟。",
    "source": "文档中「数据确认机制（Acknowledgements）」部分",
    "hint": "文档中描述了不同`acks`设置的含义，其中一种提供了“最高的一致性保证”。"
  },
  {
    "question": "在Kafka的多种复制策略中，哪一种策略的写入延迟最低，但在Leader故障时数据丢失的风险最高？",
    "options": [
      "异步复制 (Asynchronous Replication)",
      "同步复制 (Synchronous Replication)",
      "半同步复制 (Semi-Synchronous Replication)",
      "基于ISR的复制"
    ],
    "correctAnswerIndex": 0,
    "explanation": "异步复制模式下，生产者只要收到Leader副本的确认就认为消息写入成功，无需等待Follower副本的同步。这大大降低了写入延迟，提高了吞吐量。然而，如果Leader在将数据同步给Follower之前发生故障，这部分数据就会永久丢失。",
    "source": "文档中「2. 异步复制（Asynchronous Replication）」部分",
    "hint": "文档中描述了一种“注重性能的同步方式”，其缺点是“数据一致性弱”。"
  },
  {
    "question": "根据所提供的文档，ZooKeeper在Kafka集群中扮演的主要角色是什么？",
    "options": [
      "存储所有Topic分区的实际消息数据。",
      "执行分布式协调，包括管理集群元数据和选举Leader。",
      "作为客户端与Broker之间的代理，转发所有生产和消费请求。",
      "负责清理Broker上过期的日志分段文件。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档明确指出，ZooKeeper在Kafka中用于分布式协调。其核心职责包括管理集群的元数据（如Broker信息、Topic配置等）、选举分区的Leader以及进行配置管理。它不存储消息数据，也不直接参与消息的收发。",
    "source": "文档中「6. ZooKeeper」部分",
    "hint": "文档中提到：'ZooKeeper在Kafka中用于分布式协调，负责管理集群的元数据、选举Leader和配置管理等任务。'"
  },
  {
    "question": "当一个Kafka分区的Leader副本所在的Broker突然宕机时，集群会如何应对？",
    "options": [
      "该分区将永久不可用，直到宕机的Broker被手动修复并重启。",
      "所有生产者客户端会随机选择一个新的Follower副本作为写入目标。",
      "Kafka会借助ZooKeeper从该分区的ISR（同步副本集）中选举一个新的Leader副本。",
      "所有Follower副本会同时被提升为Leader，共同处理该分区的读写请求。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "这是Kafka高可用性的关键体现。当Leader故障时，Kafka的控制器（通过ZooKeeper协调）会立即从该分区的ISR中选择一个Follower作为新的Leader。因为ISR中的副本数据与原Leader是同步的，所以可以保证服务的快速恢复和数据的最小化丢失。",
    "source": "文档中「故障恢复」和「Leader 选举」部分",
    "hint": "文档在“故障恢复”章节描述了Leader故障时的应对机制，其中提到了ISR和选举过程。"
  },
  {
    "question": "Kafka引入“消费者组（Consumer Group）”这一概念的主要目的是什么？",
    "options": [
      "确保一条消息可以被同一个组内的所有消费者重复消费。",
      "实现跨多个主题的事务性消息读取。",
      "实现Topic消息消费的负载均衡和高可用，即一个分区在同一时间只被组内的一个消费者消费。",
      "对消费者进行身份认证和权限管理。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "消费者组是Kafka实现消费端横向扩展和容错的核心机制。同一个消费者组内的多个消费者会协调消费一个或多个Topic。Kafka会确保一个Topic的每个分区只被组内的一个消费者实例消费，从而将负载分散到不同的消费者上。如果组内某个消费者宕机，它负责的分区会自动被重新分配给组内其他存活的消费者。",
    "source": "文档中「5. 消费者（Consumer）」部分",
    "hint": "文档中提到：“...每个消费者组中的消费者共同消费订阅主题的消息，每个分区的消息只能被同一个消费者组中的一个消费者消费。”"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

        function loadQuestion() {
          resultContainerEl.innerHTML = '';
          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
          if (currentQuestionIndex >= quizData.length) {
            showFinalScore();
            return;
          }

          updateProgress();

          const currentQuestion = quizData[currentQuestionIndex];
          questionTextEl.textContent = `(${currentQuestionIndex + 1}/${quizData.length}) ${currentQuestion.question}`;
          
          currentQuestion.options.forEach((optionText, index) => {
            const li = document.createElement('li');
            li.className = 'option-item';
            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
                if (index === userAnswers[currentQuestionIndex]) {
                    li.classList.add('selected');
                }
            }
            optionsListEl.appendChild(li);
          });

          // 如果已经回答过，直接显示结果
          if (userAnswers[currentQuestionIndex] !== null) {
              const isCorrect = userAnswers[currentQuestionIndex] === currentQuestion.correctAnswerIndex;
              showResult(isCorrect, currentQuestion);
          }
          
          updateNavigationButtons();
          updateProgress();
        }

        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
        }
        
        function updateProgress() {
            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
        }
        
        function updateNavigationButtons() {
            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
            });
        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
                currentQuestionIndex--;
                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  